1 OzoBlockly Basic Training Lesson 4

OZOBLOCKLY BASIC TRAINING LESSON 4 Stay on the Road

ESSENTIAL QUESTION How can we make Ozobot Bit or Evo go perfectly straight when moving forward/

backward without a line?

OVERVIEW Have you noticed that Ozobot may not go completely straight when you are using the

“move forward/backward” command? This is due to hardware … Every Ozobot is a bit

different – some swerve a little to the left or right. But with a little bit of programming

help your Ozobot will go straight and follow the road!

Your students will learn how to program Ozobot Bit and Evo using OzoBlockly so that

Ozobot goes straight. They will use blocks from the advanced mode, and can

optionally create a function that can be used instead of “move forward/ backward.”

Since students are unlikely to receive the same Ozobot day-to-day, and accuracy

changes slightly over time, encourage students to learn how to change wheel bias as

a skill. They don’t need to memorize the wheel bias they’ve found today.

LESSON OUTLINE 1. Students test how Bit and Evo move forward with the “move forward” command,

and see how far their Ozobot deviates from straight.

2. Students learn how to use the “set wheel speeds” to bias the wheel movement in

order to make Ozobot go perfectly straight.

3. With this knowledge, students use their new skill to design a program

a. Optionally, students can discover how to make a function out of their program.

This function can then be called instead of using the OzoBlockly “move”

command when it is essential that Ozobot goes straight.

It’s recommended that students start to use functions, since practice helps

develop understanding quickly.

PREREQUISITES Knowledge of how to program Ozobot Bit and Evo using blocks from the Movement

category. To practice, go through OzoBlockly Basic Training Lessons 1 and 2. For

groups of students, complete Lesson 3 Pair Programming beforehand.

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GROUPING

Groups of two or three students

GRADE LEVEL Grades 2 and up

MATERIALS

• Tablet or computer with OzoBlockly editor ozoblockly.com/editor

• Ozobot Bit or Evo, one per group

• Printouts of the Test Track, one per group

• Pencil to mark Ozobot’s path

OZOBLOCKLY PROGRAMMING TOPICS Free Movement, Functions (optional)

OZOBLOCKLY MODE Modes 3 and up

DURATION 30 minutes, 50 with extension

VOCABULARY

• Ozobot Bit or Evo - Little robot that can follow drawn lines or can be programmed

using visual codes or through the OzoBlockly programming language

• OzoBlockly - A visual editor which allows you to create programs by plugging

blocks together. The blocks can be used to control Ozobot’s behavior like

movement, LED lights, etc.

• Pair Programming - two programmers work together, one as the Driver (at the

computer) and the other as the Navigator (giving ideas and directing the course).

• Steps – a unit of movement forward

• Free Movement – Ozobot’s programmed movements from OzoBlockly that do not

use line following.

• Function - a computer programming concept wherein a code that is needed

often is saved under its own name to be used any time.

• Function Call – the code block that represents the function and is used in the main

program.

QUESTIONS ABOUT THIS LESSON?

Please contact us at ozoEdu@ozobot.com

This project was developed by Ozobot and is featured on MakerHub with their permission.

For more makerspace projects, visit makerhub.demco.com.

3 OzoBlockly Basic Training Lesson 4

LESSON

PART 1: TEST MOVE FORWARD Begin by placing students into Pair Programming groups or pairs.

Students open OzoBlockly.com and explore Modes 3 and 4, and

categories Movement and Line Direction. How many different ways

can students make Ozobot move forward?

Next, hand out the track printout to your students. Point out that on the track there is a

black line that Ozobot loves to travel on, but then a dotted line it won’t be able to

follow. This thick black line is here to help Ozobot align straight before moving into

Free Movement.

Either give the correct solution or ask students for input on how they could build a

launch from the line and out into open space with the codes they’ve explored. Their

goal is to see whether and how far their Ozobot strays from the center straight line.

Write the correct answer on the board (or show them with your computer and/or

projector) which blocks they’ll need: under Line Movement use “follow line until the

next intersection or line end” followed by “move forward 10 steps at medium”.

The initial time delay allows you to adjust Ozobot on the map

This code tests the “move forward” action from Mode 3. (All students should keep

medium speed.) Each group can write the code then upload it to their Ozobot.

Double-press the power button to start the code on the bottom of the black line. What

result does each group get? Test several times and see if the deviation is always the

same.

Students use their pencils to record the location that their Ozobot lands the most at

the end of this code. Mark that location with a note like “move forward 10”.

Students have now discovered that the straight movement in the lower modes of

OzoBlockly isn’t perfectly straight. Ozobot Evo has higher accuracy than Bit, so if

you’re using an Evo you might find that adjustments are small or unnecessary.

When you see this,

have your pair programmers switch Pair Programming roles.

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PART 2: SET WHEEL SPEEDS What did your students see in the code blocks they explored that could be an

alternative to Move Forward?

Either allow students to test some ideas, or show them the answer: “set wheel speeds”

in Mode 4.

Now test the code as above, but replace “move forward 10 steps” with “set wheel

speeds”, followed by a timer for 2 or 3 seconds. It’s suggested that the students work

with 45 left and 45 right initially as the Ozobots tend to be straighter at that speed,

and it gives greater range of tweaking.

To get an idea of how they should tweak their wheel speeds, discuss or show a video

of a car taking a sharp turn. They should notice that the wheel on the inside (closest

to the corner of the turn) actually slows down while the wheel on the outside of the

turn has to be faster to account for the loss of movement from the other side. Your

students should be able to understand how that example relates to their Ozobot.

All students can now adjust wheel speeds.

They should record with a pencil the results as they go, until they get the best answer.

They should write a note with the mark of the straightest path with which wheel

speeds they chose (so 43/45 or Left 43 Right 45).

Class Responds: What is your Ozobot’s preferred wheel speeds?

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Are your students ready to learn functions? If so, skip Part 3 and go directly to the

Extension below.

PART 3: USE THE NEW METHOD

Time to play! Now we can use our new forward to go straight with additional codes.

Students code their new wheel speeds with turns and a creative dance move. Place a

repeat forever code block around the movements. Use this as a guide:

• Wait 1 second

• Forever loop around:

o Go straight

o Creative dance move and lights

o 90 degree turn or U-turn

These dances can be individually assessed by the teacher, or presented by the

students to others. Or, students could take videos of their dances to send home.

Students who add in turns may be disappointed that the turns aren’t accurate. That’s

okay, we’re going to fix that next!

6 OzoBlockly Basic Training Lesson 4

EXTENSION Functions are a fundamental part of coding. If your students are ready to learn what

a function is, then use this extension starting from the end of PART 2.

This extension is intended for classes where the first part is completed quickly.

Functions are formally introduced in Lesson 6.

DEMONSTRATION: WHAT IS A FUNCTION? Now that we have a special way of moving forward, we should save this somehow

and be able to use it at any time. That’s where functions come in.

A function is a few or many lines of code (blocks in this case) that are saved under a

special name, and can be used in the main code block whenever we want it. We

simply have to “call” the function in order to get that saved action to run. We can use

that same action once or many times in the program.

Demonstrate to students: to find Functions, go to Mode 4. The bottom of the

categories is “f(x) Functions.” We just need the first block: “to (do something)”.

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You can change the name of that ‘do something’ to be anything. If your students are

interested, you could show them camelCase.

Make a function by putting the blocks you want inside the magenta ‘do something’

block (like in example below). To use the function, use the newly created ‘goStraight’

Function Call in the Functions category, which appears in image above. You can see

‘goStraight’ is already there. That’s because the function had been created already.

Example program with goStraight function:

The function runs in the main program on the left because the Function Call is in the

main program. The function alone (right) won’t run, even if it’s on the screen, unless

it’s “called” inside the main program you’re writing (left).

Attach “goStraight” from the Functions section onto the main program, as shown in

the example above. You can use ‘goStraight’ as many times as you want.

Class Responds: Why would we make a function, instead of just putting all the code

blocks together? Possible answers are that it:

• shortens the actual running code,

• makes it easier to read for human eyes,

• is easier to edit,

• reduces bugs,

• keeps the programmer more organized,

• makes the program run more efficiently on the computer, etc.

CamelCase is a way that programmers save names for files, functions etc. In

programming languages, spaces aren’t allowed in function names, but some-

times the names need to be descriptive. That’s why we use camelCase - the first

word can be lower-case, but each following word is capitalized (yes, even those

tiny prepositions and articles), e.g., goStraight, makeAUTurn, twoMinuteDance.

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PART 4 USE THE NEW FUNCTION Time to play! Now we can use our function to go straight a few

times. Students code their goStraight function (as above) and a

special move. Students can add the following:

• fun moves in between goStraight

• spins between goStraight

• turns to complete a square

Example: Ozobot draws a square

Example: Ozobot does Travolta’s Point Move dance from Saturday Night Fever

top left: the code block that’s actually running; top right, bottom right: functions

that only run when you “call” the code “discoMoveTravolta” and “goStraight”

Students who add in turns may be disappointed that the turns aren’t accurate. That’s

okay, we’re going to fix that next!

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Test Track